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Publication Date: Friday, May 11, 2001

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Navy, residents tackle groundwater pollution below Moffett military housing 0Navy, residents tackle groundwater pollution below Moffett military housing (May 11, 2001)

By Justin Scheck

Groundwater contamination beneath a military housing complex near Moffett Field, discovered last year, is being taken up for study and discussion by Navy officials and area residents. Groundwater contamination beneath a military housing complex near Moffett Field, discovered last year, is being taken up for study and discussion by Navy officials and area residents. (May 11, 2001)

Naval researchers last year discovered chlorinated solvents -- organic compounds identified as probable and possible carcinogens -- in shallow groundwater beneath the 600-unit Orion Park housing complex last year.

While the aquifer is not used for drinking and does not come into direct contact with residents, similar groundwater pollution in other areas of Moffett Field vaporized and entered buildings.

Chemicals present beneath Orion Park include trichloroethylene (TCE) and the byproduct of its breakdown, dichloroethene. Both chemicals are suspected carcinogens and have been associated with lupus and other diseases.

The extent of the contamination in the area-and whether the contamination has left the ground-will not be known until after December, when the Navy conducts more extensive tests at Orion Park.

According to Andrea Muckerman, the Navy's environmental coordinator for the Moffett cleanup, Orion Park has 600 units, about 430 of which are occupied. She said that the number of residents fluctuates, but the Navy is trying to increase occupancy.

Source of pollutants unknown

Orion Park is a relatively small part of the Moffett complex, but the recent discovery of contamination there has raised concern, as it is one of the only contamination sites in the area that lies beneath inhabited residential buildings.

Moffett Field's cleanup, mandated under the federal EPA Superfund law, is a complex issue that has been the subject of study for years.

Now, more than a decade after cleanup efforts at Moffett began, the recent discovery of previously unknown contaminants beneath Orion Park attests to the complexity of the groundwater contamination, which could have traveled to the housing complex from any of a number of sources.

Along with old landfills and petroleum products, naval and NASA-related activities at the base led to groundwater pollution with chlorinated solvents similar, and in some cases identical, to chemicals used by the semiconductor companies in the nearby Middlefield-Ellis-Whisman (MEW) area.

Currently a federal Superfund site with office campuses built atop it, the MEW area has a number of "pump and treat" systems in place to filter chlorinated solvents out of the groundwater. But because Moffett Field lies down-gradient from the MEW area, it is difficult to identify the source of groundwater contamination.

Making matters more complicated is the fact that the pollution beneath Orion Park does not follow the contours of any known contamination plume. However, if underground water conduits are present, the contamination may be from a known plume.

According to Lenny Siegel, a Mountain View resident who is a member of the Moffett Restoration Advisory Board, the group of citizens and government officials working on the cleanup, it is rare for groundwater contamination to migrate to the surface.

But according to a Navy report from October 2000, the highest concentrations of TCE and DCE found at Orion Park were in sampling wells where the groundwater was 11 feet, 7.3 feet, and 7.4 feet below the ground.

"Given the fact that basements can go down 10 feet, it's something to be concerned about," said Siegel. Chemicals seeped into NASA office buildings

In an area of Moffett Field located above a different contaminated area, NASA officials have identified a number of buildings where chlorinated solvents from a shallow aquifer have volatilized, or evaporated, through the soil and into buildings.

Sandy Olliges, NASA's chief of environmental services at Moffett, said that most of these buildings are unused, although some have office space in them. She said the shallow aquifer in the area is between 5 and 12 feet below the ground surface.

Olliges said NASA is testing the area in preparation for developing its new research park, which she characterized as "very similar" to the brown-field redevelopment that has taken place at the old MEW sites.

Olliges said that until NASA finishes its risk assessment of the contamination beneath those buildings, she will not know the level of danger caused by the chemicals. She said that in some of the buildings it is unknown whether the contamination came from groundwater or residual chemicals left in the building.

But, Olliges added, at this point she is not concerned.

According to a March 5 study commissioned by NASA and performed by the consultants Harding ESE of Novato, Calif., chemicals including TCE, benzene, and other volatile organic compounds (VOCs) were found in vapor form in a number of buildings located in the area of the planned research park. While the chemicals were present at relatively low levels, some exceeded the Environmental Protection Agency's cleanup standard.

"Eight VOCs were detected above the EPA Region 9 Preliminary Remediation Goals (PRGs), adjusted for a residential exposure scenario of 24 hours per day over 20 years," in a 1999 testing program, the report indicates.

A January 1999 study to evaluate whether vapors from groundwater contamination migrated into a building at Moffett found that TCE and another solvent, 1,1,1-TCA, were present in the building.

According to the report, an additional air study "indicated that the building was not suitable for use as a child-care center, due primarily to elevated levels of benzene and 1,4-dioxane."

The report concludes that although the chemicals present in the groundwater around these buildings are "unlikely to pose a hazard to onsite workers" because of their low concentrations, a number of VOCs were detected "above adjusted PRGs for a residential scenario, indicating that VOC infiltration may be an issue for any residential development."

According to Ted Smith, director of the Silicon Valley Toxics Coalition, a San Jose-based group that advocates the cleanup of toxic sites, a Superfund site in Sunnyvale exhibited volatilization of TCE from a shallow aquifer into the basements of residents in the San Miguel neighborhood.

Smith said that until it is known whether volatilization is occurring at Orion Park, it will be impossible to determine the level of exposure to residents. But he said that the shallow depth of the groundwater, the occurrence of volatilization at nearby sites, and the close proximity of the contamination to Stevens Creek raise questions about residents' safety.

Smith also questioned why the Navy is waiting until December to determine whether residents are being exposed to the contaminants.

"If I lived there, based on what I know, I would certainly be concerned and try to get these people to do the testing before December... You would think they would be jumping on it. I don't know why they're not," said Smith.

Muckerman said that a "preliminary risk assessment indicated the (Orion Park) site is safe for residential [use]."

She said that upcoming studies and risk assessments will evaluate the "worst-case scenario" for long-term chemical exposure.

"This scenario will be evaluated as if someone was to inhabit the house for 30 years... If the worst-case scenario shows the housing is safe, we have a good comfort level," Muckerman said.

She said the Navy is also investigating the potential for contamination to flow into Stevens Creek, which runs adjacent to Orion Park. Since chemicals can volatilize and harm wildlife if they enter the creek, Muckerman said evaluating this risk will be a key part of the Navy's December study.


 

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